Band assignments, Raman

The infrared and Raman spectra of many alkyl and arylthiazoles have been recorded. Band assignment and more fundamental work has been undertaken on a small number of derivatives. Several papers have been dedicated to the interpretation of infrared spectra (128-134, 860), but they are not always in agreement with each other. However, the work of Chouteau (99, 135) is noteworthy. The infrared spectrum of thiazole consists of 18 normal vibrations as well as harmonic and combination bands. 

The complex structure of the various solutions was investigated by Raman and IR absorption spectroscopy. Containers made of sapphire and KRS-5 were used for Raman and IR spectra measurements, respectively. Vibration spectra analysis was performed based on the band assignment [171, 187] presented in Table 45. 

The infra-red measurements were of two types, normal-film measurements with the sample sandwiched between KBr plates, and tilted-film experiments with the sample sandwiched between 45° prisms of KBr, in each case with layers of Nujol to provide optical matching. Whereas the 1616 cm 1 Raman line occurs in a region well clear of other lines so that it was satisfactory to measure peak intensities, the infra-red spectrum of PET shows many overlapping bands. Accurate assessment of absorption intensities therefore requires the computer separation of the spectrum into a set of overlapping peaks (shown to be Lorentzian in profile) and a linear background. The procedures adopted and the band assignments are discussed in detail by Hutchinson et al. 6). 

Saito, S. and Tasumi, M. 1983. Normal-coordinate analysis of P-carotene isomers and assignments of the Raman and infrared bands. J. Raman Spectrosc. 14 310-321. 

B. Raman Optical Activity Band Assignments for Folded Proteins. 60... 

Resonance Raman Spectroscopy as a Complement to Other Techniques for Making Electronic Band Assignments for (Re2X8)2 Ions... 

The O H stretching spectra of ethanol trimers and larger clusters cannot be conformationally resolved in a slit jet expansion [65, 77, 157], VUV-IR spectra [184] are even broader, sometimes by an order of magnitude, and band maxima deviate systematically by up to +50 cm 1 from the direct absorption spectra. We note that ethanol dimers and clusters have also been postulated in dilute aqueous solution and discussed in the context of the density anomaly of water ethanol mixtures [227], Recently, we have succeeded in assigning Raman OH stretching band transitions in ethanol-water, ethanol water, and ethanol water2 near 3550, 3410, and 3430cm, respectively [228],... 

Table 1 Band Assignments for Resonance Raman Bands of BIPS in Different Solvents...

The vibration bands relative to phosphate groups in the apatite structure differ from the normal modes of the P04 isolated ion, due to distortions of the PO4 tetrahedra in the apatite lattice and vibrational coupling [4]. Therefore, site-group and factor-group analyses were applied [15,16,18,21] to elucidate the vibrational spectra observed (Fig. 5) and band assignments of infrared (IR) and Raman bands have been given (Table 3). 

A comparative spectral study (IR and laser Raman) among 4i/-imidazoles and their 1- and 3-oxides and their 1,3-dioxides showed that a band assigned to a Vc=N out-of-plane vibration was very sensitive to the position of the N-oxide group. ... 

The picosecond IR absorption spectrum of the tS state in the fingerprint region is different in w-heptane and in acetonitrile. The spectrum recorded for Si tS in the nonpolar solvent w-heptane is consistent with a species that has a center of symmetry. In acetonitrile, the spectrum exhibits additional weak bands near 1570, 1250, and 1180 cm which are approximately at the same frequencies as strong Raman bands assigned to in-plane vinylic vibrational modes in 5i. This result was taken to suggest a molecular structure for 5i that lacks a center of symmetry in acetonitrile. However, because the intensities of these three bands are weak, it was concluded that either the polarization of 5i or the contribution from polarized S structures to all of the S structures in acetonitrile may be small. 

Table la. Infrared and Raman Band Assignments for EPON 828 17)... 

In liquid ammonia, Raman spectroscopy indicated that the major species present was the tetraammine.24 This was based on the observation that the band assigned as y(N—Ag—N)Sym at 370 cm-1 in aqueous solutions was absent in liquid ammonia, whilst a new band occurred at 290cm-1. Also, whilst no tetraammine salts have been isolated from aqueous solution, recrystallization of [Ag(NH3)2]C104 from liquid ammonia yielded [Ag(NH3)4]C104. 

Raman Infrared Raman Infrared Raman Infrared Raman Infrared Class Band assignment"... 

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